JP3920476B2 - Multilayer electroluminescence device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electroluminescence (hereinafter abbreviated as EL) element used in, for example, a display device, and more particularly to a multilayer EL element in which a plurality of thick film EL elements are stacked on a transparent substrate.
[0002]
[Prior art]
One of the required specifications of the display design is a requirement to display a specific pattern simply by emitting light in a plate shape during normal display and inputting a designation signal. In the case of a thick film type EL element, conventionally, the light emitting surface is divided in a plane and the entire surface is made to emit light or only a specific part is made to meet the above requirement.
[0003]
[Problems to be solved by the invention]
By the way, there is a problem that the pattern contour cannot be emitted when the entire surface emits light, so that the contour is visible and the design property is impaired. In particular, a pattern that does not emit light when the entire surface emits light when the entire surface emits light is used as a backlight of a display device such as a liquid crystal provided on the front side, and when light is emitted at a specific location, characters and pictures are raised from the back. The presence of the contour makes it difficult to see the character display on the display device, which is obstructive and has the disadvantage that the display quality deteriorates.
[0004]
An object of the present invention is to eliminate such disadvantages of the prior art and provide a multilayer EL element having high display quality.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention sequentially forms a first phosphor layer, a transparent dielectric layer, an intermediate transparent electrode, a second phosphor layer, a dielectric layer, and a back electrode on a transparent substrate with a transparent electrode. The transparent substrate side transparent electrode, the first phosphor layer, the transparent dielectric layer, and the intermediate transparent electrode constitute a first thick film electroluminescent element, and the intermediate transparent electrode, the second phosphor layer, and the dielectric layer And the back electrode constitute a second thick film electroluminescent element, the first thick film electroluminescent element emits light entirely without being patterned , and the second thick film electroluminescent element is the second thick film electroluminescent element . The phosphor layer and the dielectric layer have substantially the same shape as the first phosphor layer, the transparent dielectric layer, and the intermediate transparent electrode of the first thick film electroluminescence element, and only the back electrode has a desired shape. And characterized in that it is the turn training.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a cross-sectional view of a multilayer EL element according to Embodiment 1 of the present invention. In the figure, 1 is a transparent substrate with a transparent electrode, 2 is a first phosphor layer, 3 is a transparent dielectric layer, 4 is a transparent electrode, 5 is a second phosphor layer, 6 is a dielectric layer, and 7 is a back surface. Electrodes 8 are resist layers, which are sequentially stacked as shown.
[0007]
The transparent substrate 1 is made of a transparent synthetic resin film such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polyimide having a thickness of 75 to 125 μm, for example, on the surface facing the first phosphor layer 2, for example, ITO. A transparent electrode (not shown) is formed.
[0008]
The first phosphor layer 2 is prepared by using a high-dielectric constant resin such as cyanoethyl resin (for example, product name CR-S manufactured by Shin-Etsu Chemical Co., Ltd.) as a binder and adjusting the viscosity, and a moisture-proof coating is applied thereto. The phosphor powder (for example, product name TYPE10 luminescent color orange manufactured by Sylvania) is dispersed, and this paste is dried on the transparent substrate 1 (transparent electrode) by a method such as screen printing to have a dry film thickness of 30 to 60 μm (in this embodiment) 50 μm), and then heated to volatilize the organic solvent.
[0009]
The transparent dielectric layer 3 is made of a high dielectric constant resin such as cyanoethyl resin (for example, product name CR-S manufactured by Shin-Etsu Chemical Co., Ltd.), in order to increase the voltage applied to the first phosphor layer 2 and increase the luminance. It is formed by dissolving the solvent in a solvent and adjusting the viscosity with a technique such as screen printing so that the dry film thickness is 3 to 8 μm (5 μm in this embodiment) and then heating to volatilize the organic solvent. The
[0010]
The transparent electrode 4 is prepared by dissolving a transparent binder such as a polyester resin such as PET in an organic solvent and dispersing an appropriate amount of ITO powder. The paste is screened on the transparent dielectric layer 3. After printing so as to have a dry film thickness of 5 to 20 μm (10 μm in this embodiment) by a technique such as printing, it is formed by heating and volatilizing the organic solvent.
[0011]
The second phosphor layer 5 is prepared by dissolving a high dielectric constant resin such as a cyanoethyl resin (for example, product name CR-S manufactured by Shin-Etsu Chemical Co., Ltd.) in an organic solvent as a binder, and has a moisture-proof coating applied thereto. An appropriate amount of the phosphor powder (for example, product name TYPE40 emission color blue green manufactured by Sylvania) is added and dispersed, and the paste is applied to the transparent electrode 4 by a method such as screen printing to have a dry film thickness of 30 to 60 μm (this embodiment) It is formed by printing so as to have a thickness of 50 μm) and then heating to volatilize the organic solvent.
[0012]
The dielectric layer 6 has a cyanoethyl resin (for example, product name CR-V manufactured by Shin-Etsu Chemical Co., Ltd.) or a fluororesin (for example, manufactured by Daikin Industries, Ltd.) in order to increase the voltage applied to the second phosphor layer 5 and increase the luminance. A high dielectric constant resin such as product name G-501) is dissolved in an organic solvent to adjust the viscosity, and then a high dielectric constant material such as barium titanate is dispersed in the film to a dry film thickness of 10 to 20 μm by a method such as screen printing. After printing so as to be 10 μm in this embodiment, it is formed by heating and volatilizing the organic solvent.
[0013]
The back electrode 7 is prepared by dissolving a transparent resin binder such as polyester resin such as PET in an organic solvent to adjust the viscosity, and dispersing an appropriate amount of conductive powder such as silver, carbon black, or graphite. It is formed by printing on the dielectric layer 6 so as to have a dry film thickness of 5 to 15 μm (10 μm in this embodiment) by a method such as screen printing, and then heating to volatilize the organic solvent.
[0014]
The resist layer 8 is provided to ensure insulation and moisture resistance, and a plastic sol type insulating paste in which a thermoplastic resin such as vinyl chloride or polyester is dispersed in a liquid plasticizer such as dioctyl phthalate (DOP). As shown in FIG. 1, the paste is dried over the outer periphery of the dielectric layer 6 and the second phosphor layer 5 from above the back electrode 7 to a dry film thickness of 5 to 15 μm (15 μm in this embodiment). After coating, the organic solvent is volatilized by heating.
[0015]
The cyano resin is a resin obtained by reacting acrylonitrile with a polymer having a hydroxyl group as a raw material, and has a highly polar cyano group (—CN) in the side chain. It has a high relative dielectric constant.
[0016]
Product name G-501 made by Daikin Industries, Ltd. used as the fluororesin is a vinylidene fluoride-hexafluoropropylene fluororesin, which uses a polyamine vulcanizing agent and has a high relative dielectric constant of about 12-15. Show. Further, the relative dielectric constant of barium titanate added to the dielectric layer 6 is usually 1000 to 3000, and other dielectric powders such as titanium oxide (relative dielectric constant is usually 60 to 80) can be used in the present invention. .
[0017]
In this embodiment, the first phosphor layer 2, the transparent dielectric layer 3, and the transparent electrode 4 constitute a first thick film EL element, and the second phosphor layer 5, the dielectric layer 6 and the back electrode 7 are the first. 2 thick film EL elements are formed. However, the transparent electrode 4 is also used for light emission of the second thick film EL element. The second phosphor layer 5 and the dielectric layer so that the first thick film EL element emits light on the entire surface, and the second thick film EL element emits light in a desired pattern shape different from that of the first thick film EL element. 6 and the back electrode 7 are patterned.
[0018]
As described above, the two phosphor layers of the first phosphor layer 2 and the second phosphor layer 5 are provided, and the place where the voltage is applied is between the transparent substrate 1 (transparent electrode) and the transparent electrode 4, and the transparent electrode 4. And the back electrode 7 can be changed to display two colors of light.
[0019]
In this embodiment, since the emission color of the first phosphor layer 2 is orange and the emission color of the second phosphor layer 5 is blue green, a voltage is applied between the transparent substrate 1 (transparent electrode) and the transparent electrode 4. When applied, orange light is emitted, and when a voltage is applied between the transparent electrode 4 and the back electrode 7, blue-green light is emitted.
[0020]
In the present embodiment, the combination of the orange and blue green emission colors has been described. For example, a combination with other phosphors such as blue (product name TYPE 20 manufactured by Sylvania), purple (product name TYPE 60 manufactured by Sylvania), or other fluorescence Combinations between bodies are also possible.
[0021]
In the EL element according to the present embodiment, an insulating resist layer 8 having a thickness larger than that of the back electrode 7 is laminated on the outer surface (lower surface) of the back electrode 7. Therefore, it is difficult for external moisture to reach the phosphor layers 2 and 5 from the back electrode 7 side, and the phosphor layers 2 and 5 use phosphor powder with a moisture-proof coating. Even if it reaches the body layers 2 and 5, the phosphor powder is not adversely affected and the life of the EL element can be extended.
[0022]
The resist layer 8 is formed by printing and drying a plastic sol type insulating paste mainly composed of a thermoplastic resin. This plastic sol type insulating paste does not use an organic solvent as a dispersion medium. High stability, printability is almost the same even when printing for a long time, and since the content of film forming components is high, a sufficient film thickness can be secured even with one printing, and the printing process is simplified. Can be achieved. Furthermore, the plastic sol type insulating paste is less likely to cause pinholes due to air bubbles during printing and drying, and a high-density coating film is obtained. Further, since isocyanate is added as a coupling agent to this insulating paste, the adhesion between the back electrode 7 and the resist layer 8 is good, and an excellent moisture-proof effect can be obtained from this point as well.
[0023]
As described above, when the dielectric layer 6 is formed using the binder mainly composed of a fluororesin, the moisture resistance of the dielectric layer 6 is improved. On the other hand, the cyano resin that is the binder of the second phosphor layer 5 has a higher dielectric constant and better dispersibility of the phosphor powder than the fluororesin, so that the EL element has high luminance and good light emission quality. .
[0024]
(Embodiment 2)
FIG. 2 is a cross-sectional view of a multilayer EL element according to the second embodiment of the present invention. In the figure, 1 is a transparent substrate with a transparent electrode, 2 is a first phosphor layer, 9 is a semi-transparent dielectric layer, 4 is a transparent electrode, 5 is a second phosphor layer, 6 is a dielectric layer, and 7 is a back surface. Electrodes 8 are resist layers, which are sequentially stacked as shown.
[0025]
In the case of this embodiment, the translucent dielectric layer 9 is prepared by dissolving a high dielectric constant resin such as cyanoethyl resin (for example, product name CR-S manufactured by Shin-Etsu Chemical Co., Ltd.) in an organic solvent and adjusting the viscosity, for example, mica, pearl, A white powder such as titanium oxide or barium titanate is added and dispersed so as to have a dry film thickness of 3 to 8 μm (5 μm in this embodiment) by screen printing or the like, and then heated to form the organic It is formed by volatilizing the solvent.
[0026]
The second phosphor layer 5 is prepared by dissolving a high dielectric constant resin such as a cyanoethyl resin (for example, product name CR-S manufactured by Shin-Etsu Chemical Co., Ltd.) in an organic solvent as a binder, and has a moisture-proof coating applied thereto. Phosphor powder (product name TYPE40, emission color blue green, manufactured by Sylvania), fluorescent pigments and fluorescent dyes are added in an appropriate amount to change the emission color, and the paste is screen printed on the transparent electrode 4. After printing so as to have a dry film thickness of 30 to 60 μm (50 μm in this embodiment) by the above method, it is formed by volatilizing the organic solvent by heating to form a colored phosphor layer.
[0027]
Examples of the fluorescent pigment include Sinloich FA001 to 009, and examples of the fluorescent dye include rhodamine B.
[0028]
In this embodiment, the first phosphor layer 2, the translucent dielectric layer 9 and the transparent electrode 4 constitute a first thick film EL element, and the second phosphor layer 5, the dielectric layer 6 and the back electrode 7. A second thick film EL element is configured so that the first thick film EL element emits light on the entire surface, and the second thick film EL element emits light in a desired pattern shape different from that of the first thick film EL element. In addition, the second phosphor layer 5, the dielectric layer 6, and the back electrode 7 are patterned.
[0029]
(Embodiment 3)
FIG. 3 is a cross-sectional view of a multilayer EL element according to the third embodiment of the present invention. This embodiment is different from the first and second embodiments in that the light emitting layer composed of the second phosphor layer 5 and the dielectric layer 6 of the second thick film EL element is the first thick film. It has substantially the same shape as the EL element [first phosphor layer 2, transparent dielectric layer 3 (or transflective dielectric layer 9), transparent electrode 4], and only the back electrode 7 is patterned into a desired shape. ing.
[0030]
In the above embodiment, the first thick film EL element is constituted by a single thick film EL. However, the first thick film EL element may be constituted by a plurality of thick film ELs.
[0031]
【The invention's effect】
The present invention according to claim 1 is a method of sequentially forming a first phosphor layer, a transparent dielectric layer, an intermediate transparent electrode, a second phosphor layer, a dielectric layer and a back electrode on a transparent substrate with a transparent electrode, The transparent substrate side transparent electrode, the first phosphor layer, the transparent dielectric layer, and the intermediate transparent electrode constitute a first thick film electroluminescent element, and the intermediate transparent electrode, the second phosphor layer, the dielectric layer, and the back surface is the second thick-film electroluminescent element composed of electrodes, said first thick film electroluminescent device entirely emission is not patterned, the second phosphor of the second thick-film electroluminescent device The layer and the dielectric layer have substantially the same shape as the first phosphor layer, the transparent dielectric layer, and the intermediate transparent electrode of the first thick film electroluminescence element, and only the back electrode is patterned into a desired shape. And it is characterized in that it is grayed. By adopting such a configuration, it is possible to provide a multi-layer EL element with a high display quality that makes it difficult to see the outline of the display portion.
[0032]
According to the second aspect of the present invention, since the first thick film EL element and the second thick film EL element have different emission colors, the display colors can be enriched, that is, the number of colors can be increased.
[0033]
According to the third aspect of the present invention , since the dielectric layer is formed of a dielectric resin, an inexpensive thick film EL element can be provided.
[0034]
In the present invention according to claim 4, the dielectric resin is specified as a cyano resin or a fluorine resin. Since the cyano resin has a high dielectric constant, the voltage applied to the phosphor layer can be increased to increase the luminance. In addition, the fluororesin provides a dielectric layer with excellent moisture resistance, and thus the life of the EL element can be extended.
[0035]
According to the fifth aspect of the present invention, the dielectric layer of the first thick film EL element is a translucent dielectric layer. In the present invention described in claim 6, since the translucent dielectric layer is a film in which white powder is dispersed and held in a transparent resin binder having a high dielectric constant, the phosphor layer of the first thick film EL element is It becomes a reflective layer and can prevent the emission color from shifting.
[0036]
According to the seventh aspect of the present invention, since the dielectric layer of the second thick film EL element is a film in which a high dielectric constant powder is dispersed and held in a resin binder having a high dielectric constant, the voltage applied to the phosphor layer is controlled. You can increase the brightness.
[0037]
The present invention according to claim 8 comprises a film in which a phosphor powder having a phosphor layer coated with moisture-proof is dispersed in a resin binder. In the present invention according to claim 9, the resin binder is a fluororesin. For this reason, the phosphor can be effectively prevented from being deteriorated by moisture, and the quality can be improved.
[0038]
In the tenth aspect of the present invention, since the resin binder is a cyano resin, the dispersibility of the phosphor powder is good, and the luminous quality can be improved with high luminance.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a multilayer EL element according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of a multilayer EL element according to a second embodiment of the present invention.
FIG. 3 is a cross-sectional view of a multilayer EL element according to a third embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 1st fluorescent substance layer 3 Transparent dielectric material layer 4 Transparent electrode 5 2nd fluorescent substance layer 6 Dielectric material layer 7 Back electrode 8 Resist layer 9 Translucent dielectric material layer

Claims (11)

A first phosphor layer, a transparent dielectric layer, an intermediate transparent electrode, a second phosphor layer, a dielectric layer and a back electrode are sequentially formed on a transparent substrate with a transparent electrode,
The transparent substrate side transparent electrode, the first phosphor layer, the transparent dielectric layer, and the intermediate transparent electrode constitute a first thick film electroluminescent element, and the intermediate transparent electrode, the second phosphor layer, the dielectric layer, and the back surface A second thick film electroluminescent element is constituted by the electrode,
The first thick film electroluminescent device emits light entirely without being patterned ,
The second phosphor layer and the dielectric layer of the second thick film electroluminescence element have substantially the same shape as the first phosphor layer, the transparent dielectric layer, and the intermediate transparent electrode of the first thick film electroluminescence element. A multilayer electroluminescent device, wherein only the back electrode is patterned into a desired shape .   2. The multilayer electroluminescent element according to claim 1, wherein the first thick film electroluminescent element and the second thick film electroluminescent element have different emission colors.   2. The multilayer electroluminescent device according to claim 1, wherein the dielectric layer is made of a dielectric resin.   4. The multilayer electroluminescent element according to claim 3, wherein the dielectric resin is a cyano resin or a fluorine resin.   4. The multilayer electroluminescent device according to claim 3, wherein the dielectric layer of the first thick film electroluminescent device is a translucent dielectric layer.   6. The multilayer electroluminescent device according to claim 5, wherein the translucent dielectric layer is a film in which white powder is dispersed and held in a transparent resin binder having a high dielectric constant.   4. The multilayer electroluminescent element according to claim 3, wherein the dielectric layer of the second thick film electroluminescent element is a film in which a high dielectric constant powder is dispersed and held in a resin binder having a high dielectric constant.   4. The multilayer electroluminescent device according to claim 3, wherein the phosphor layer is a film in which a moisture-proof coated phosphor powder is dispersed in a resin binder.   9. The multilayer electroluminescent element according to claim 8, wherein the resin binder is a fluororesin.   9. The multilayer electroluminescent device according to claim 8, wherein the resin binder is a cyano resin.   7. The multilayer electroluminescent element according to claim 5, wherein the phosphor layer of the second thick film electroluminescent element contains a fluorescent pigment or a fluorescent dye.

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